1. Field of the Invention
The present invention relates to a plasma display panel (PDP) and, more particularly, to a front substrate of the PDP and its fabrication method.
2. Description of the Background Art
In general, with the development and growing spread of in an information processing system, an importance of a next-generation multimedia display device as a visual information transmission means is increasing. Especially, because a conventional CRT (Cathode Ray Tube) fails to go with the recent tendency aiming at a large and flat screen, researches on an LCD (Liquid Crystal Display), an FED (Field Emission Display), a PDP (Plasma Display Panel), and an EL (ElectroLuminesence) are actively ongoing.
As a self-emission display device using a plasma gas discharge, the PDP is advantageous in that it can be enlarged in size, its picture quality is excellent and an image response speed is fast.
In addition, the PDP receives an attention in the market as a wall-mounted display device together with the LCD or the like.
A discharge cell of a three-electrode AC surface discharge type PDP having such characteristics will now be described with reference to FIG. 1.
FIG. 1 illustrates a structure of a general three-electrode AC surface discharge type PDP.
As shown in FIG. 1, the general three-electrode AC surface discharge PDP is constructed such that a front substrate 10 and a back substrate 20 are coupled and a discharge gas is injected therebetween.
The front substrate 10 includes: an upper glass substrate 11; transparent electrode 12 and bus electrode 13 formed on the glass substrate; an upper dielectric layer 14 formed entirely on the transparent and bus electrode-formed upper glass substrate 11; and a protection layer 15 formed on the upper dielectric layer 14.
The upper dielectric layer 14 serves to limit a plasma discharge current and accumulate a wall charge when plasma is discharged.
The back substrate 20 includes: a lower glass substrate 25; an address electrode 24 formed on the lower glass substrate 25; a lower dielectric layer 23 formed entirely on the address electrode-formed lower glass substrate 25; a barrier rib 22 formed on the lower dielectric layer 23; and a phosphor 21 formed entirely on the lower dielectric layer 23 and the barrier rib 22.
The operation principle of the general PDP constructed as described above will now be explained.
First, as a discharge sustain voltage is applied to the transparent electrode 12 and the bus electrode 13, charges are accumulated on the upper dielectric layer 14, and as a discharge starting voltage is applied to the address electrode 24, a discharge gas comprising He, Ne and Xe or the like injected in each discharge cell of the PDP is separated to electron and ion to turn to plasma.
Thereafter, in the PDP, when the phosphor 21 is excited by ultraviolet generated at a moment when the electron and ion are re-coupled, a visible light is generated by which a character or a graphic is displayed. Herein, in order to prevent thermal deformation of the dielectric layer or the phosphor 21 caused as the accelerated gas ions collide with each other, the PDP uses Ne gas having a relatively greater molecular weight as a principal component.
However, since Ne gas generates an orange-colored visible light (585 nm) when discharged, color purity and a contrast of the PDP deteriorate.
In order to avoid such a problem, a PDP having a color filter layer or a black strip layer additionally formed on the upper substrate has been proposed.
FIG. 2 is a sectional view showing a front substrate of the PDP in accordance with a conventional art.
As shown in FIG. 2, the front substrate of the conventional PDP includes an upper substrate 11; transparent electrode 12 and bus electrode 13 formed on the upper glass substrate 11; an upper dielectric layer 14 formed on the transparent and bus electrode-formed upper glass substrate 11; a color filter layer 14A formed on the upper dielectric layer 14; and a protection layer 15 formed on the color filter layer 14A. The color filter layer 14A can control a light transmittance and prevent a surface reflection by an external light.
Accordingly, in the conventional PDP, the color purity of the PDP can be enhanced by controlling the light transmittance of a color filter by virtue of the color filter layer, and the contrast of the PDP can be enhanced by preventing a surface reflection by an external light.
However, in the conventional PDP, formation of the color filter layer on the upper dielectric layer of the PDP complicates a fabrication process of the PDP.
In addition, in the conventional PDP, since the light transmittance of a blue (B) visible light is relatively low compared to the red (R) and green (G) visible light, the color temperature of the PDP is approximately 6000K. Thus, in order to compensate the low color temperature, input signals corresponding to R, G and B are controlled, the barrier rib structure is formed asymmetrically or the light transmittance and dye of the color filter layer are controlled, but in this case, the luminance of the PDP is reduced.
Meanwhile, the color filter layer may be replaced by a black stripe layer. However, the black strip layer has a small aperture plane, a light emitting efficiency of the PDP is degraded.
As mentioned above, the conventional PDP has the following problems.
That is, since the color filter layer is additionally included, the fabrication process of the PDP is complicated.
In addition, since the light transmittance of the B visible light is relatively low compared to the R and G visible light, the color temperature of the PDP is low.